#11 diffuse -c does not work with git branch merge operations

[Uffe Jakobsen]

diffuse -c is unable to extract the list of involved files from a git merge operation between branches.

This makes diffuse unusable for reviewing large (git) merge commits with lots of involved files (it simply does not work)

This patch fixes the above issue.
The fix is simply to switch from "git log" to "git show" for "-c" operations.
This fix should have no side effects as "git show" works on top of "git log".

/Uffe

[Derrick Moser]

Thanks for the patch.